diff --git a/authlib/integrations/base_client/sync_app.py b/authlib/integrations/base_client/sync_app.py
index 3716c0dd..18d10d08 100644
--- a/authlib/integrations/base_client/sync_app.py
+++ b/authlib/integrations/base_client/sync_app.py
@@ -317,7 +317,8 @@ def create_authorization_url(self, redirect_uri=None, **kwargs):
 
 
         with self._get_oauth_client(**metadata) as client:
-            client.redirect_uri = redirect_uri
+            if redirect_uri is not None:
+                client.redirect_uri = redirect_uri
             return self._create_oauth2_authorization_url(
                 client, authorization_endpoint, **kwargs)